Russia's opposition plans to stage new nationwide demonstrations on Saturday, expected to attract tens of thousands of people to protest alleged rigging of December 4 parliamentary elections. Incensed by claims of wholesale violations in the polls that handed a reduced majority to Vladimir Putin's ruling party, tens of thousands of people already took to the streets across Russia on December 10. Those protests were the biggest show of public anger in Russia since the chaotic 1990s and the first sign of a growing challenge to Putin's 12-year domination of the country. A coalition of opposition forces, encouraged by that success, have called a new rally on Sakharov Avenue at 1000 GMT in Moscow, with almost 50,000 people vowing on Facebook to attend. Other protests are expected elsewhere in Russia from Vladivostok in the Far East to the exclave of Kaliningrad on the border with the European Union. Among those attending in Moscow may be the Soviet Union's last leader Mikhail Gorbachev, 80, who has been virulently critical of the elections, although his spokesman emphasised it would depend on how he felt on the day. Gorbachev said in an interview with the Novaya Gazeta on Friday that he was ashamed by Putin's reaction to the protests, after the Russian strongman compared the white ribbons worn by demonstrators to condoms. Charismatic anti-Kremlin blogger Alexei Navalny is also expected to be present after his release from prison following a brief sentence for his participation in a protest shortly after the elections. President Dmitry Medvedev Thursday proposed a package of reforms in an apparent bid to appease the protestors, including the resumption of direct elections for governors and a simplified procedure to register political parties. But it is unlikely the moves will satisfy protestors who want the government to annul the ballot results, sack election commission chief Vladimir Churov, and hold a new vote. In the face of the protests, the newly elected lower house of parliament, the State Duma, held its first session on Wednesday. "People are demanding the punishment of the guilty, the sacking of Churov," top opposition leader Vladimir Ryzhkov told AFP. "People do not want to live with the fraudulent Duma for the next five years." The ruling United Russia party won less than half the vote in the elections and lost 77 seats as fatigue set in with the 12-year rule of Putin, who is planning to win his old Kremlin job back in March polls and could stay in power until 2024. The opposition says the party's performance would have been even worse in free elections.